1. Field of the Invention
The present invention relates to a vehicle brake hydraulic pressure control system including a hydraulic pressure supply source which outputs hydraulic pressure, a hydraulic pressure control unit which is interposed between the hydraulic pressure supply source and wheel brakes for adjusting hydraulic pressures at the wheel brakes, a brake hydraulic pressure detecting unit which detects hydraulic pressures at the wheel brakes, and a controller which includes a target wheel brake pressure setting unit which sets target hydraulic pressures for the wheel brakes for controlling the operation of the hydraulic pressure control unit so that the hydraulic pressures at the wheel brakes become target hydraulic pressures set by the target wheel brake pressure setting unit.
2. Description of Related Art
A vehicle brake hydraulic pressure control system like this has already been known in, for example, Japanese Patent Unexamined Publication No. JP-A-2006-137382.
Conventionally, in controlling hydraulic pressures at wheel brakes of a vehicle, it is general practice to determine in advance target hydraulic pressures for the wheel brakes, pressure reducing thresholds which are higher than the target hydraulic pressures and pressure build-up thresholds which are lower than the target hydraulic pressures and compare brake pressures at the wheel brakes which are detected with the target hydraulic pressures, the pressure reducing thresholds and the pressure build-up thresholds to determine “pressure reduction,” “pressure holding,” and “pressure build-up.”
As this occurs, as shown in FIG. 16A, when the pressure reducing thresholds and pressure build-up thresholds are made to approach the target hydraulic pressures in order to enhance the control accuracy, the brake pressures at the wheel brakes go past the pressure reducing thresholds and the pressure build-up thresholds at one breath to produce an overshoot.
On the other hand, as shown in FIG. 16B, when the holding area is expanded by moving the pressure reducing thresholds and the pressure build-up thresholds away from the target hydraulic pressures, the control accuracy is deteriorated.
Therefore, according to the JP-A-2006-137382, although thresholds are prepared for use according to the control modes, when attempting to enhance the response of the lamps, the brake pressures change in a stepped fashion as shown in FIG. 16C, producing mode hunting.